• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.10-17
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• 2004

The Doowoo-ri tidal flat in the southwestern Korean coast is a typical open-coast tidal flat which has no barriers in the offshore such as barrier island and sand bars. The difference of induced wave energy with seasons is affected directly on the distribution of surface sediment and the formation of sedimentary structures because the sedimentation by wind wave is relatively much important element in this open-coast tidal flat. This open-coast tidal flat can be classified into tidal beach, intertidal flat and lower mudflat according to the pattern of geomorphology and sediment type. The intertidal flat can be again divided into 3 types: sand flat, mixed flat and mud flat based on the primary sedimentary structure and sand/mud ratio. Doowoori tidal flat shows a seasonal change in the surface sedimentary facies based on sediment composition and primary sedimentary structure. The change is closely related to the direction and magnitude of monsoon wind and also to storm frequency. In winter and spring, when northwesterly wind is most dominant and strong and also storms are common, sand-flat facies is largely distributed on the intertidal flat, whereas mud-flat facies is most dominant during summer when weak southeasterly wind is common. In the fall season, mixed-flat facies is dominant on the flat. The Doowoori intertidal flat is covered by mud sediment which is ca. 20 cm in thickness in summer season. In winter season, surface sediment is changed from mud to sand because the summer mud is mostly eroded by strong wave action. Can-core peels in the intertidal flat show that parallel laminated mud or sand/mud and climbing ripple cross-laminated sandy silt are dominant on the upper intertidal flat $(0-1.3 {\cal}km)$ during summer season. On the other hand, on lower intertidal flat $(1.7-2.3 {\cal}km)$, dominant sedimentary facies is homogeneous mud. In winter, it is changed into parallel laminated and ripple cross-laminated sand facies.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.5 no.1
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• pp.26-32
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• 2002

Purpose: Constipation in childhood is a significant problem, however, understanding of its epidemiology has been limited in Korea. The aim of this study was to investigate the prevalence and risk factors of constipation in school-aged children, helping to manage and prevent it. Methods: This cross-sectional, descripsive observational prevalence study included children (2grade, 1st and 6th grade) who were attending two elementary schools in Gwangju. The prevalence of constipation, associated symptoms, and risk factors were evaluated by questionnaire. A child was considered to be constipated when he or she defecated two or less times per week. Results: The prevalence of constipation was 15.4%. There is no significant difference between both sexes and grades. Of the causes of constipation, there was statistically significant difference in exercise deficiency, frequent intake of convenience food, long-time watching TV, unbalanced diet and enuresis history between constipation and normal group. Especially, long-time watching TV, exercise deficiency, and enuresis history were risk factors for development of constipation. Only 27.1% of children with constipation were treated by laxative and enema. Conclusion: Even though the prevalence of constipation was high, more than half of them was not treated at all. We should endeavor to educate the children and their parents to prevent constipation by evaluating the feeding and behavioral habit completely, and treating them properly.

• Pediatric Infection and Vaccine
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• v.9 no.1
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• pp.79-84
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• 2002

Purpose : About 41% of obtained group A streptococci in the 1998 was reported as erythromycin-resistant streptococci in Seoul, Korea. The most common T serotype was T12, followed by T4 and T28. We'd like to monitor the serological changes and antibiotic sensitivity test of Streptococcus pyogenes obtained from the patients with pharyngotonsillitis and invasive diseases from 1999 through 2001. Also, it could be proposed to choose the proper antibiotic selection in the area where the rate of erythromycin-resistant streptococci is high. Methods : From Jan. 1999 to Oct. 2001, 208 isolates of group A streptococci were collected from inpatients and outpatients with pharyngotonsillitis, scarlet fever, and invasive infections in Seoul and Southern part of peninsula. All isolates were serotyped by T-agglutination, minimum inhibitory concentrations(MICs) which were determined by agar dilution methods, according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). Results : The most common T serotype was T12(29.8%), followed by T1(23.1%), T4 (14.9%). T1 was prominent serotype compared with previous year. T serotyping, among 25 isolates obtained from the patients with scarlet fever in Southern part of peninsula mostly, was T12, T1, and T4 in order of frequency. All the isolates tested were susceptible to penicillin, cefprozil, vancomycin, ceftriaxone, and chloramphenicol. However, 23 isolates(14.2%) was resistant to erythromycin and 18 isolates(11.1%) was resistant to clarithromycin. Serotype T12 was found to be the most resistant serotype to erythromycin and/or clarithromycin. Conclusion : High rate of erythromycin-resistant streptococci which surveyed in 1998 were reduced to 14.2% in this study. We should have to further evaluate the reason of decreased resistant strains and consider the resistant strains of streptococci in choosing the antibiotics. There was no serological characteristics according to the types of disease entities. Between the serologic distributions in Seoul and the Southern part of peninsula area are same, we could presume that the serological typing of strains obtained over the country may be not different.

• Pediatric Infection and Vaccine
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• v.4 no.2
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• pp.232-239
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• 1997

Purpose: The incidence of hepatitis A virus(HAV) infection has markedly decreased in the last 20 years due to industrialization and improvements in the standard of living and hygiene in Korea. The reduction in seroprevalence rates indicates infection potential for young adult population, and a need for vaccinations in high-risk adults and children groups has been suggested. In this study we evaluated the seroprevalence rates and natural infection rates of hepatitis A in children and adolescent to obtain the basic data for vaccination of hepatitis A. Methods: A total of 334 children and adolescent subjects below 20 years old in Kyonggi-do province were examined for HAV antibody and seroprevalence rates in each age group was investigated. In 584 elementary school students residing in Kyonggi-do province, serum samples collected in 1993 and 1996 from the same subjects for investigation of natural seroconversion rates. Method of testing antibody was enzyme immunoassay. Results: 1) The seropositive rate of HAV in 334 subjects aged below 20 years old was 5.4%. According to age, the seropositive rates were 27.3% in infant group, 0.0% in 1~4 year-old group, 0.0% in 5~9 year-old group, 2.9% in 10~14 year-old group and 15.0% in 15~19 year-old group. 2) In the study of 584 elementary school children, only one subject showed seropositive in 1993, and in 1996 three different subjects showed seropositive results(0.5%); the natural seroconversion rate during 3 years was 0.5%. 3) The seroprevalence rates of below 20 year-old subjects reported in previous studies were 63.8% in 1979 and 47.3% in 1989 while the present study showed the rate at 5.4%. Conclusion: Since natural antibody formation is rarely occurring, there is a high risk for apparent hepatitis A infection in adults. Therefore vaccination in high risk groups is essential at present, and in order to reduce the chance for hepatitis A infection in adults, vaccination in children may be needed.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.109-116
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• 2011

Purpose : Pneumococcus is one of the most important causes of invasive infection through the childhood period. In January 2008, the Clinical and Laboratory Standards Institute (CLSI) published revised penicillin breakpoints for Streptococcus pneumoniae and penicillin susceptibility rates of S. pneumoniae increased in Korea. This study was performed to determine the probability of oral amoxicillin for the empirical treatment achieving bactericidal exposure against pneumococcus using pharmacodynamics model. Methods : Twenty-three isolates of pneumococci were subjected to determine minimum inhibitory concentration (MIC) for ${\beta}$-lactams and macrolide. For the ${\beta}$-lactams, exposure of fT >MIC (time that free drug concentrations remain above the MIC) for 50% of the administration interval have determined the probability of target attainment (PTA), and regimens that had a PTA >90% were considered optimal. An analysis was performed by applying MIC of 23 isolates to a 5000-patient Monte Carlo simulation model. Results : Among 23 isolates from healthy children, 7 (30.4%) isolates were MIC ${\leq}$1.0 ${\mu}g$/mL and 19 (82.6%) were MIC ${\leq}$2 ${\mu}g$/mL for amoxicillin. Amoxicillin 40 mg/kg/day achieved PTA >90% at MIC ${\leq}$1.0 ${\mu}g$/mL but PTA decreased to 52% at MIC 2 ${\mu}g$/mL, whereas amoxicillin 90 mg/kg/day can predict 97% of PTA at MIC 2 ${\mu}g$/mL. Overall, oral amoxicillin 90 mg/ kg/day for the empirical treatment against pneumococcus can expect more successful response in Korean children. Conclusion : Considering the resistantce pattern of pneumococci in Korean children, we estimate that oral amoxicillin 90 mg/kg/day will provide a pharmacodynamic advantage for the empirical treatment against pneumococcus. And low dose amoxicillin or macrolide are expected to have higher chance of treatment failure than high dose oral amoxicillin.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.154-162
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• 2011

Purpose : The aim of this study was to identify the clinical characteristics of lower respiratory tract infection due to respiratory syncytial virus (RSV) in young children and to provide information for an effective guideline for palivizumab administration in Korea. Methods : We reviewed medical charts of 167 patients under 3 years of age who were hospitalized in Dongguk University Ilsan Hospital for lower respiratory tract infection between January 2007 and February 2011. Diagnosis of the virus was made based on the multiplex real time polymerase chain reaction. Results : There were 113 patients who were infected by respiratory syncytial virus. 90 patients were term infants and 23 patients were preterm infants. No difference was shown between term and preterm infants except the days of admission which was 9.0${\pm}$6.0 days and 12.6${\pm}$21.0 days respectively. In the preterm group their mean age at the time of admission was 5.21${\pm}$4.9 months and the mean gestational age was 33.1${\pm}$4.3 weeks, and the mean birth weight was 2,152${\pm}$950 g. Only 4 patients were born under 28 weeks gestational age and were candidates for palivizumab administration. Conclusion : Most of the patients with severe RSV lower respiratory tract infection were term or near term infants who were not candidates for palivizumab prophylaxis. A nationwide study is needed to make a new risk stratified guideline for RSV prophylaxis for our country.

• Pediatric Infection and Vaccine
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• v.16 no.1
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• pp.61-72
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• 2009

Purpose : We evaluated the clinical features of Norovirus gastroenteritis compared with Rotavirus gastroenteritis in hospitalized children. Methods : We detected causative agents in 3,261 samples of children hospitalized with gastroenteritis symptoms at a single center of pediatrics between 2005 and 2006. Among 266 and 303 samples which tested positive for Norovirus and Rotavirus, we selected 73 and 182 samples of children with relatively pure gastroenteritis symptoms and retrospectively analyzed the corresponding medical records. Results : The male-to-female ratio of the Norovirus (+) and Rotavirus (+) groupswas 1.43:1 and 1.56:1 both groups were predominantly in males. The mean age of the Norovirus (+) and Rotavirus (+) groups was 36.7 and 24.4 months, respectively the children in the former group were older than the children in the latter group. The incidence in the Norovirus (+) group was more concentrated in the winter. The symptoms in the Norovirus (+), in decreasing order, included vomiting, diarrhea, and fever. The duration of vomiting, diarrhea, and fever was 2.1, 1.2, and 1.2 days. The maximum number of episodes of vomiting and diarrhea per day was 3.5 and 4.5, respectively. The severity score was 10.16. The symptoms inthe Rotavirus (+) group, in decreasing order, included diarrhea, vomiting, and fever. The duration of diarrhea, vomiting, and fever was 2.2, 4.3, and 2.2 days, respectively. The maximum number of episodes of vomiting and diarrhea per day was 3.3 and 6.5, respectively. The severity score was 11.9. The severity in the Norovirus (+) group was somewhat lower than the Rotavirus (+) group. The younger the child, the more severe the symptoms in the Norovirus (+) group. There was no difference between mono-and co-infection in severity and between the two groups regarding the hematologic findings. Conclusion : Based on the findings reported herein, additional studies about prophylaxis, as well as the epidemiology and clinical features of pediatric Norovirus gastroenteritis, are required.

• Pediatric Infection and Vaccine
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• v.24 no.2
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• pp.79-86
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• 2017

Purpose: This study was aimed at analyzing the serotypes of group B streptococcus (GBS) isolated from Korean infants with invasive disease and evaluating their association with disease manifestation. Methods: Data were retrospectively collected from invasive GBS infections at Gachon University Gil Medical Center from January 2006 to June 2012 and at Samsung Medical Center from April 2010 to November 2012. Serotypes were determined by slide agglutination test. Results: A total of 37 cases were identified, which included 22 full-term infants and 15 preterm infants. Fifteen cases (40.5%) were early-onset, 19 (51.4%) was late-onset, and three (8.1%) was very late-onset. Early-onset diseases among preterm infants were higher than those among full-term infants (60.0% [9/15] vs. 27.3% [6/22], P=0.17). The most common manifestation was bacteremia (70.3%), followed by meningitis and septic arthritis. Among 24 isolates retrievable for serotyping, serotype III (41.7%) was most common, followed by V (16.7%), Ia, Ib, and II (12.5%, respectively), and non-typeable (4.2%). Serotype III was more common in isolates from full-term infants (10/22) than from preterm infants (0/15), whereas serotype V was more common in isolates from preterm infants (4/15) than from full-term infants (0/22) (P=0.002). No penicillin-resistant strain was detected, and resistance to erythromycin and clindamycin were both 64.9%. Conclusions: GBS is an important pathogen in both preterm and full-term infants, and serotype distribution of GBS causing invasive diseases can differ between preterm and full-term infants. It is necessary to monitor the nationwide epidemiology of GBS diseases, including in preterm infants, in order to prepare preventive measures without underestimating early-onset diseases.

• Pediatric Infection and Vaccine
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• v.24 no.2
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• pp.95-101
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• 2017

Purpose: Acute bacterial gastroenteritis (ABG) can cause more severe symptoms than acute viral gastroenteritis in children. This study was aimed at determining the etiologic trends and to examine the clinical characteristics of ABG in children. Methods: We sent stool samples from the children with acute gastroenteritis who were treated at a secondary hospital located in Seoul, Korea between January 2011 and December 2014 to Seoul Metropolitan Government Research Institute of Public Health and Environment to find the causative organisms. Clinical characteristics of patient were analyzed through a medical records review. Results: Out of 664 stool samples, 183 (27.6%) yielded bacterial pathogens. Staphylococcus aureus was the most common bacterial pathogen, found in 72 cases (39.3%), even though it was only tested for since 2012. The monthly isolation rate was the highest (24.6%) in August. The isolation rate of Campylobacter spp. by patient's age group was high (16.7%) in the 12- to 18-year-age group (P=0.04). In patients with bloody stool, Campylobacter spp. was the most commonly isolated (31.0%, P=0.04). When comparing C-reactive protein, the Salmonella spp.- or Campylobacter spp.-isolated group showed higher values than the S. aureus- or pathogenic Escherichia coli-isolated group ($5.7{\pm}0.6mg/dL$ vs. $2.1{\pm}0.3mg/dL$, P<0.01). Conclusions: S. aureus, Salmonella spp., pathogenic E. coli, and Campylobacter spp. were important pathogens of ABG among children. Considering the differences in pathogens found according to age, a clinical symptom and inflammation index might be helpful in assuming the causative organism.

• Pediatric Infection and Vaccine
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• v.24 no.2
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• pp.71-78
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• 2017

Purpose: The aim of this study was to identify the pathogens of blood stream infection (BSI) in children with hemato-oncologic disorders, to analyze susceptibility patterns of microorganisms to guide empirical antimicrobial therapy, and to compare temporal trends of the pathogen and antimicrobial susceptibility with those of previous studies. Methods: We retrospectively analyzed the medical records of children with hemato-oncologic disorders whose blood culture grew pathogens at the Seoul National University Children's Hospital between 2011 and 2015. Results: A total of 167 patients developed 221 episodes of bacteremia. Among 229 pathogens, gram-negative bacteria (GNB) accounted for 69.0% (64.0% in 2002 to 2005, 63.4% in 2006 to 2010); gram-positive bacteria (GPB) accounted for 28.8% (31.3% in 2002 to 2005, 34.6% in 2006 to 2010); and fungus accounted for 2.2%. Among GNB, Klebsiella species (53.2%, 84/158) and Escherichia coli (19.6%, 31/158) were common. Staphylococcus aureus (48.5%, 32/66) and viridans streptococci (21.2%, 14/66) were frequently isolated among GPB. The susceptibilities of oxacillin and vancomycin in GPB were 54.8% and 96.9% (51.5% and 95.5% in 2002 to 2005; 34.1% and 90.5% in 2006 to 2010), respectively, whereas in GNB, the susceptibilities of cefotaxime, piperacillin/tazobactam, and imipenem were 73.2%, 77.2%, and 92.6% (75.9%, 82.8%, and 93.4% in 2002 to 2005; 62.8%, 82.9%, 93.8% and in 2006 to 2010), respectively. There were no significant differences in the proportion of etiologic agents or the antimicrobial susceptibilities between the current study and that of the previous two studies from 2002 to 2010. Overall fatality rate was 13.1%. Conclusions: GNB predominated in BSI among children with hemato-oncologic disorders. The etiology of bacteremia and antimicrobial susceptibility were comparable to those of the previous studies. Thus, piperacillin/tazobactam can be used as the initial empirical antimicrobial agent in febrile neutropenia.